1. Field of the Invention
The present invention relates to the discovery of a specific class of plasticizers for poly(iminoimidazolidinediones) and poly(parabanic acid) resins.
2. Related Art
Both the poly(iminoimidazolidinediones) and poly(parabanic acids) and their method of preparation are known and described in detail in commonly assigned U.S. Pat. No. 3,661,859, which is incorporated in its entirety herein. The poly(parabanic acids) may also be prepared by other processes, such as shown in U.S. Pat. No. 3,609,113.
The poly(iminoimidazolidinediones) may be formed by the reaction of hydrogen cyanide with a diisocyanate or mixture of diisocynates, the reaction of a dicyanoformamide with a diisocyanate or mixtures of diisocyanates, or the polymerization of a cyanoformamidyl isocyanate and contain a 1,3-imidazolidinedione-1,3-diyl ring of the following structures in the repeat units: ##STR3## wherein NH is in the 4 or 5 position.
The poly(parabanic acids) also designated as poly(1,3-imidazolidine-2,4,5-triones) may be prepared, for example, by the acid hydrolysis of poly(iminoimidazolidinediones) and contain the imidazolidinetrione ring in the repeat unit: ##STR4## U.S. Pat. No. 3,609,113 and German Pat. No. 1,770,146 describe other methods for preparing polymers which contain the poly(parabanic acid) ring.
The polymers may contain both imino-1,3-imidazolidinedione-1,3-diyl rings and imidazolidinetrione rings, thus the present polymers may be broadly characterized as having the repeating unit: EQU --Q--R--.sub.n
wherein Q is ##STR5## wherein X is O or NH, provided that at least one X is O, R is an organic moiety which may be aliphatic, alicyclic, aromatic or mixtures thereof, and n is sufficiently large to produce a solid product.
The R is the organic moiety of the diisocyanate when the polymer is produced according to the procedure in U.S. Pat. No. 3,661,859. Thus, the diisocyanates may be selected from a broad group having a large variety of organic moieties. The organic moieties of the diisocyanate may be substituted with groups such as alkyl, aryl, halogens, sulfoxy, sulfonyl, alkoxy, aryloxy, oxo, ester, alkylthio, arylthio, nitro and the like which do not react with the isocyanate group. Functional groups which have active hydrogen atoms, (e.g., carboxylic acids, phenols, amines, etc.) should not be present. Specific diisocyanates which may be used are set out in U.S. Pat. No. 3,661,859, other patents, articles or organic textbooks as known in the art.
Some of the parabanic acid polymers have been found to have high glass transition temperatures, and thus are especially suitable as magnetic tapes (where good dimensional stability at high temperatures is required), films for use in flexible printed circuits, cable wraps, etc., for fibers such as tire cord fibers (where tensile strength and modulus are required), for moldings for electrical connectors, bearings, magnetic wire insulation, coatings for cables, cookware, glass fabrics, industrial belts (where high temperatures are required) and the like.
However, many of the present polymers decompose when they are heated at or above their glass transition temperatures and as a result they can not be molded or extruded. Previously these polymers could be processed only by solution methods or by a powder coating technique which also requires a solvent.
It is an advantage of the compositions of the present invention that the poly(iminoimidazolidinediones), poly(imidazolidine-2,4,5-triones) or mixed poly(iminoimidazolidine-1,3-dione/imidazolidine-2,4,5-triones) or as defined above the polymers --Q--R].sub.n may be processed by extrusion and molding techniques, when plasticized according to the present invention. Also films of the compositions of the present invention can be heat-sealed whereas films of the same pure polymers cannot be sealed with heat.
U.S. Pat. No. 3,901,847 commonly assigned discloses that poly(parabanic acids) may contain small amounts, i.e., 2.5 to 15 weight % of specific phosphonates and phosphates, particularly the halogenated analogues of these compounds as flame retardants. There is a broad disclosure of aryl phosphates, however, the only unhalogenated aryl phosphate evaluated was tris(biphenyl)phosphate. The other data was developed for halogenated phosphates and polyphosphates. Some of the materials actually evaluated by the patentee embrittled the polymers, even at the low levels employed.
According to the present invention a specific class of organic phosphates at high concentrations have been found to be compatible with the poly(parabanic acids) and in fact the present organic phosphates are plasticizers for the polymers and exhibit a quite opposite effect to the embrittlement which is an apparent effect of some organic phosphates evaluated in U.S. Pat. No. 3,901,847.
Japanese application No. 53045-355, filed Oct. 7, 1976 (TOA NENRYO KOGYO K.K.) also discloses polymeric phosphates as flame retardants in amounts of 1-20 parts by weight.